U.S. Frost Dates by Weather Station

NOAA station USC00111265 · Illinois

Frost Dates for Carbondale, IL

NOAA weather station Carbondale Sewage Plant (USC00111265), Illinois · elevation 390 ft (119 m) · hardiness zone 7a*

  • Lower-risk planting dateafter April 25only 1 spring in 10 still has a frost later
  • Typical last frostApril 950% chance of a frost after it
  • Typical first fall frostOctober 2250% chance of a frost before it
  • Frost-free season195 daystypical year, 32°F
  • Hardiness zone7acalculated*

The year at a glance

Frost season at Carbondale, ILSpring: a frost after March 25 in 9 years out of 10, after April 9 in half of the years, after April 25 in 1 year out of 10. Fall: the first frost comes before October 10 in 1 year out of 10, before October 22 in half of the years, before November 2 in 9 years out of 10. Typical frost-free season: 195 days.JanFebMarAprMayJunJulAugSepOctNovDecLast frost ~Apr 9First frost ~Oct 22Frost season at Carbondale, ILSpring: a frost after March 25 in 9 years out of 10, after April 9 in half of the years, after April 25 in 1 year out of 10. Fall: the first frost comes before October 10 in 1 year out of 10, before October 22 in half of the years, before November 2 in 9 years out of 10. Typical frost-free season: 195 days.JFMAMJJASONDLast frost ~Apr 9First frost ~Oct 22
frost likely chance fading 90% → 10% frost-free in a typical yearThe year at a glance. Blue: frost is likely; the gradient fades as the chance drops from 90% to 10%; green: the frost-free part of a typical year.

Frost dates (32°F)

Probability of frost, based on 29 years of NOAA records (1991–2020 normals)
ChanceLast frost in spring afterFirst frost in fall before
10% (unlikely)April 25October 10
50% (typical)April 9October 22
90% (likely)March 25November 2
Frost-free season (32°F, 50% chance)
195 days
Hard frost (28°F), last in spring, 50% chance after
March 29
Hard frost (28°F), first in fall, 50% chance before
November 1

The last 15 years (2006–2020 normals)

Typical last frost April 8 (1 day earlier than the 30-year normal), typical first fall frost October 24 (2 days later). Frost-free season 197 days.

A shorter, more recent NOAA period. The 30-year normals above remain the main reference: 15 years carry more year-to-year noise.

Add these dates to your calendar Yearly reminders for the typical last frost, the lower-risk planting date and the typical first fall frost (.ics).

How the chance of frost changes with the date

Spring at Carbondale: chance of a frost after this dateSpring, chance of a frost after the date: 10% April 25, 20% April 20, 30% April 16, 40% April 12, 50% April 9, 60% April 5, 70% April 2, 80% March 30, 90% March 25. Observed last spring frost in recent years: 2021 April 23, 2023 April 3, 2024 April 6, 2025 April 8, 2026 March 18.Spring: last frostChance of a frost after this date10%50%90%Apr 1May 1Apr 25Apr 9Mar 252021: April 232023: April 32024: April 62025: April 82026: March 18Fall at Carbondale: chance of a frost before this dateFall, chance of a frost before the date: 10% October 10, 20% October 14, 30% October 18, 40% October 20, 50% October 22, 60% October 24, 70% October 27, 80% October 30, 90% November 2. Observed first fall frost in recent years: 2023 October 31, 2024 October 16, 2025 November 10.Fall: first frostChance of a frost before this date10%50%90%Oct 1Nov 1Oct 10Oct 22Nov 22023: October 312024: October 162025: November 10
Two charts, because spring and fall answer different questions: in spring, the chance that a frost still comes after a date; in fall, the chance that the first frost has already come before it. NOAA publishes these odds from 10% to 90%, so the lines stop there. ◆ marks the actual date in each recent year.

What actually happened in recent years

Observed dates of the last spring and first fall frost (32°F) at this station; ◆ marks them on the charts above
YearLast spring frostFirst fall frost
2021April 23incomplete record
2022incomplete recordincomplete record
2023April 3October 31
2024April 6October 16
2025April 8November 10
2026March 18season not over yet

What these dates mean

The 195 days between the 32°F 50% dates in Carbondale frame a span in which light frosts are less likely than not, with the spring median on April 9 and the fall median on October 22. For a cautious planting plan, gardeners should aim to set out tender crops after the spring cautious date of April 25, when there is only a 10 % chance of a later frost, and should finish harvesting tender crops before the fall cautious date of October 10, when there is only a 10 % chance that a frost has arrived earlier. The hard-frost median dates are March 29 in spring and November 1 in fall; a hard frost at 28 °F can damage plants that would otherwise survive a light frost at 32 °F.

How to read the probabilities

The dates are probabilities from 30 years of weather, not a forecast for this year.

  • Spring: "10% after April 25" means that in about one spring out of ten a frost still happens after that date. The 90% date is the earliest: a frost after it happens in most years.
  • Fall: "10% before October 10" means that in about one fall out of ten the first frost arrives before that date.
  • 50% is the typical date: half of the years are earlier, half are later.
  • A light frost (32°F) damages tender plants; a hard frost (28°F) also stops most hardy vegetables.

Nearby weather stations

Map of weather stations near Carbondale, ILNumbered nearest stations: 1 — Jackson, MO — 37 mi; 2 — Perryville, MO — 41 mi; 3 — Cape Girardeau, MO — 41 mi; 4 — Nashville, IL — 44 mi; 5 — Rosiclare, IL — 45 mi.ILMOKYIN25 mi · 40 km1. Jackson, MO — 37 mi12. Perryville, MO — 41 mi23. Cape Girardeau, MO — 41 mi34. Nashville, IL — 44 mi45. Rosiclare, IL — 45 mi5
  1. Jackson, MO 37 mi (59 km)
  2. Perryville, MO 41 mi (66 km)
  3. Cape Girardeau, MO 41 mi (67 km)
  4. Nashville, IL 44 mi (70 km)
  5. Rosiclare, IL 45 mi (72 km)

Sources

* Hardiness zone 7a: zone derived from PRISM 2023 grid at the station location (not the official USDA map). Source data: PRISM Group, Oregon State University.

Station coordinates: 37.7308, -89.1658.